The Physiology Core will provide integrated services to the researchers of the individual projects. The Core personnel will work to coordinate physiological testing of animals with each individual project directors. The auditory brainstem response will be the primary method to evaluate auditory sensitivity across all projects. The endocochlear potential will be measured to address the status of stria vascularis in young and old mice. The Physiology Core will also coordinate noise exposures of animals with respect to each investigator's needs for exposures that will produce either temporary (ITS) or permanent (PTS) threshold shifts to meet the needs of the projects. The Physiology Core will provide all of the standard materials and services to accomplish the physiological measurements. The results obtained from the procedures described in this core will be analyzed and coordinated for statistical significance with the Data Management team and they will serve as consultants to discuss interpretation of data and correlation with other results. The Core will analyze and prepare graphs for presentation at scientific forums and publication in scientific journals. To further promote efficient and successful Core operation, frequent meetings will be used to discuss progress in research, emerging techniques and assist in future directions. Procedures are in place for scheduling and prioritization of services and quality control. The Histology Core and Physiology Core will work closely together to coordinate physiological and morphological characterization of animals under experimental conditions.